We present a series of aspherical lenses and diffraction gratings 3D printed for use as optical components in terahertz spectroscopy systems. Commercially available plastics for 3D printing (VisyJet Crystal, Acrylonitrile Butadiene Styrene (ABS) Plastic and acrylic based polymers) have also been characterized via Terahertz Time Domain Spectroscopy (TDS) and two-color wave photomixing. In addition, characterization has been achieved using synchrotron radiation at the Australian Centre for Synchrotron Science. The lenses were found to have a focal length of (35±2) mm suggesting high spatial resolutions might be achieved. This result agrees with the calculated focal length of 35.5 mm. Control over output maxima and beam splitting of the diffraction gratings is observed with easily made adjustments in the 3D printing design process. A square grating produced was found to be a (78±2)% efficient beam splitter. The blazed grating produced demonstrated an efficiency of (38±1)% in the first order diffraction maxima. These were taken using radiation at 0.28 THz using the two-color wave photomixing system.